Grand Canyon Trail (1948) on Netflix

Plot summary

Sintown was a silver town once, and now its mines are worked out and its buildings stand empty. J. Malcolm Vanderpool has money in the claim, and when the venture comes apart his secretary, Carol Martin, passes herself off as his daughter and goes west to find silver and rescue the company. The engineer on the payroll, Regan, intends to keep any silver he finds for himself. Only Old Ed Carruthers, an old prospector, knows where the main lode lies. Roy Rogers and the singing ranchers of the Riders of the Purple Sage are in the territory, and Old Ed's mule Genevieve is with them.